fun quicksort(numbers:List<Int>):List<Int> = 
    if (numbers.isEmpty())
            numbers
    else{
            val pivot  = numbers.first()
            val tail = numbers.drop(1)
            val lessOrEqual =  tail.filter{e-> e <= pivot}
            val larger = tail.filter{ e-> e > pivot}
            quicksort(lessOrEqual) + pivot + quicksort(larger)
        }
    

println(quicksort(listOf(10,1,4,20,16)))